The present invention relates to an insulating member using an abrasion-resistant resin composition. Precisely, the invention relates to such an insulating member which is usable in any severe service conditions, for example, in the inner structure of automobiles.
Polyolefin resin is widely used since it is light and easy to shape and has good mechanical strength in some degree. When the resin is desired to have higher strength and elasticity, glass fibers, talc, clay, calcium carbonate and the like may be added to it. However, the additives may detract from the workability of the resin and may increase the weight thereof and, as the case may be, they may worsen the outward appearance of shaped articles of the resin. Therefore desired is polyolefin resin that is free from the drawbacks.
For example, lightweight bicomponent fibers of polypropylene and polyamide with no interfacial separation of the constituent components are disclosed in, for example, Japanese Patent Publication Nos. 3-279419A (page 2), 4-272222A (page 2) and 4-281015A (page 2). These are core/sheath fibers, and the object disclosed is to improve the colorability of polypropylene in the fibers. The method disclosed for the fibers comprises high-speed spinning through a spinning nozzle with small orifices and treating the thus-spun fibers with solvent or melting them, and its object is to obtain ultrafine fibers having a fineness of from 0.1 to 1 denier (d). Therefore, the productivity in the method is poor, and the method is uneconomical. The fibers are continuous ultrafine fibers and are therefore good material for woven fabrics and synthetic leather that are glossy and have a good feel. However, when filled in and mixed with rubber or resin, they are difficult to knead and disperse since they are continuous fibers.
In Kobunshi Kagaku, Vol. 29, No. 324, 265 (1972), and Kobunshi Ronbunshu, Vol. 47, No. 4, 331 (1990), disclosed is a nylon/polypropylene blend with a small amount of maleic anhydride-modified polypropylene added thereto. In this, the compatibility of the two constituent components with each other is improved, and the particle size of the dispersion particles is extremely reduced to improve the mechanical properties (impact resistance, tensile strength) of the polymer blend. However, the mechanical properties of the polymer blend having a blend ratio of around 50/50 are extremely poor. A composition of polyamide fibers finely dispersed in a polyolefin matrix is disclosed in, for example, Japanese Patent Publication No. 11-106570A (page 1). This composition is hopeful as a reinforcing material for rubber and resin, and when a polyolefin is added thereto, the workability, the strength and the elasticity of the resulting composition are enhanced.
Japanese Patent Publication No. 11-302464A (page 1) discloses a composition that contains from 90 to 99 parts by weight of a polyolefin and from 1 to 10 parts by weight of polyamide fibers. This composition has good shaping workability and is lightweight, and its strength, elasticity and dimensional stability are all good. However, the composition disclosed in this publication is not improved in point of the abrasion resistance thereof.
On the other hand, for example, various resinous insulating members are used in the inner structure of automobiles. The inner structure of automobiles that comprises such insulating members is all the time in severe conditions, for example, exposed to high temperature, shock, vibration, and scattering of oily matter such as oil and fuel.
Heretofore, various resinous insulating members have been used for automobile parts in different sites to satisfy different heat resistance, oil resistance, impact resistance, abrasion resistance and dimensional stability. For these, for example, used are various resins and rubbers such as polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), Teflon (trademark), polyethylene terephthalate (PET), nylon (PA), ethylene-ethyl acrylate copolymer (EEA), ethylene-vinyl acetate copolymer (EVA), polyether-sulfone (PES), polyimide, polyphenylene sulfide (PPS), polyether-nitrile (PEN), olefin-based elastomer, styrene-based elastomer, polybutylene terephthalate (PBT), nylon 6 (PA6), nylon 66 (PA66), nylon 46 (PA46), nylon 6T (PA6T; HPA), polyphenylene ether (PPE), polyoxymethylene (POM), polyarylate (PAR), polyetherimide (PEI), liquid-crystalline polymer (LCP), cyclic olefin copolymer (COC), polymethylpentene (PMP), PP alloy, PA66 alloy, polycarbonate (PC), acryl, silicone, ethylene-propylene-diene tercopolymer (EPDM), chloroprene, urethane, polyethylene chloride, nitrile and nitrile rubber (NBR). Optionally two or more different types of these resins and rubbers may be combined. The applications of these resinous materials are specifically defined depending on their own intrinsic characteristics. However, when the resinous materials are used only directly as they are, they are not satisfactorily resistant to the severe conditions as in the inner structure of automobiles.
Resinous insulating members to be in the inner structure of automobiles are differentiated by coloration in prescribed colors (red, white, black, blue, green, etc.) for easy construction, wiring and interconnection of the parts. For coloring wires, heretofore employed is a method of kneading dye or pigment in insulating resin while the resin is shaped through extrusion, in which the coating layer of the resin is homogeneously colored to the depth thereof. However, the method is problematic in that the line must be stopped every time for color change and the material loss is therefore great. This means that the productivity in the method is not good and the colored wires of not so much use will be much in stock.